uninstall.php

<?php 
if( !defined('ABSPATH') || !defined('WP_UNINSTALL_PLUGIN') ){
	die();
}

$options = get_option( 'fa_plugin_options', array() );
if( isset( $options['settings']['complete_uninstall'] ) && $options['settings']['complete_uninstall'] ){
	// 1. Remove plugin options
	delete_option('fa_plugin_options');
	
	// 2. Remove Custom Post Slider
	$args = array(
		'post_type' => 'fa_slider',
		'post_status' => 'any'
	);
	$sliders = get_posts( $args );	
	if( $sliders ){
		foreach( $sliders as $slider ){
			wp_delete_post( $slider->ID, true );
		}
	}
	
	// 4. Remove Slide Options from other posts used as slides
	global $wpdb;
	$query = "DELETE FROM {$wpdb->postmeta} WHERE meta_key = '_fa_slide_settings'";
	$wpdb->query( $query );
	
	// 5. Delete transients
	delete_transient('fa_version');
}